The present invention relates to a cleansing composition comprising an N-long chain acylamino acid or a salt thereof which composition is excellent in foaming power, foam breakage and feeling after its use.
Inorganic salts and organic salts of N-long chain acylamino acids have bactericidal activity in addition to surface activity. Cleansing agents comprising these salts are mild to skin and have an excellent detergency, and thus are widely used as a main component of cleansing compositions (Japanese Published Examined Patent Application No. 38604/79, Japanese Published Examined Patent Application No. 83538/93 and Japanese Published Examined Patent Application No. 27720/85).
Among the salts of N-long chain acylamino acids used as cleansing agents, salts of N-long chain acylamino acids of tertiary amide type are excellent in water-solubility, but are known to have the defects that much rinse is necessary for breaking the foam generated and that they give a slimy feeling. Salts of N-long chain acylamino acids of secondary amide type are known to be disadvantageous in that the foam is not stable enough for cleansing and that they give a poor feeling after their use. To solve these problems, it is known to use an N-long chain acyldipeptide in combination with an N-long chain acylamino acid (Japanese Published Unexamined Patent Application No. 78693/93).
N-acylglutamine is known to have hair-growing activity (Japanese Published Unexamined Patent Application No. 32726/94) and melanin formation inhibiting activity (Japanese Published Unexamined Patent Application No. 157284/94), but its use as a cleansing agent is not known.
The present invention provides a cleansing composition comprising at least one compound selected from N-long chain acylamino acids represented by formula (I): 
(wherein n represents 1 or 2; and R represents a saturated or unsaturated hydrocarbon group having 5 to 23 carbon atoms), and salts thereof [hereinafter referred to as Compound (I)].
Examples of the saturated hydrocarbon group having 5 to 23 carbon atoms in the definition of Compound (I) are straight-chain or branched-chain ones such as pentyl, isopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl, docosyl, and tricosyl. Examples of the unsaturated hydrocarbon group having 5 to 23 carbon atoms are straight-chain or branched-chain ones such as pentenyl, 3-methyl-1-butenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, nonadecenyl, eicosenyl, heneicosenyl, docosenyl, tricosenyl, 1,3-pentadienyl, 8,11-heptadecadienyl, 8,11,14-heptadecatrienyl, and 4,7,10,13-nonadecatetraenyl.
Preferred examples of the saturated hydrocarbon group are saturated straight-chain or branched-chain hydrocarbon groups having 11 to 17 carbon atoms such as undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, and heptadecyl. Preferred examples of the unsaturated hydrocarbon group are unsaturated straight-chain or branched-chain hydrocarbon groups having 11 to 17 carbon atoms such as undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, 1,3-pentadienyl, 8,11-heptadecadienyl, and 8,11,14-heptadecatrienyl.
Examples of the salts in Compound (I) are alkali metal salts such as sodium salt, potassium salt, and lithium salt, alkaline earth metal salts such as calcium salt and magnesium salt, ammonium salt, amine addition salts such as salts with monoethanolamine, diethanolamine, triethanolamine, and triisopropanolamine, and basic amino acid addition salts such as salts with arginine and lysine.
Illustratively, the N-long chain acylamino acid consists essentially of 1-8 mol% N-octanoyl glutamine or a salt thereof, 3-10 mol% N-decanoyl glutamine or a salt thereof, 45-53 mol% N-dodecanoyl glutamine or a salt thereof, 16-25 mol% N-tetradecanoyl glutamine or a salt thereof, 5-10 mol% N-hexadecanoyl glutamine or a salt thereof, 2-10 mol% N-octadecanoyl glutamine or a salt thereof, 4-17 mol% N-octadecanoyl glutamine or a salt thereof, and 0-2 mol% N-octadecadienoyl glutamine or a salt thereof; or 1-8 mol% N-octanoyl asparagine or a salt thereof, 3-10 mol% N-decanoyl asparagine or a salt thereof, 45-33 mol% N-dodecanoyl asparagine or a salt thereof, 16-25 mol% N-tetradecanoyl asparagine or a salt thereof, 5-10 mol% N-hexadecanoyl asparagine or a salt thereof, 2-10 mol% N-octadecanoyl asparagine or a salt thereof, 4-17 mol% N-octadecanoyl asparagine or a salt thereof, and 0-2 mol% N-octadecadienoyl asparagine or a salt thereof.
Compound (I) can be prepared by converting a straight-chain or branched-chain fatty acid having 6 to 29 carbon atoms which is saturated or unsaturated (hereinafter referred to as a long chain fatty acid) into halides such as chloride and bromide by the use of halogenating agents such as thionyl chloride and phosgene, and then condensing the halide with an amino acid selected from glutamine and asparagine (hereinafter referred to simply as an amino acid). Alternatively, Compound (I) can be prepared by converting a long chain fatty acid into an acid anhydride, and then reacting the acid anhydride with an amino acid.
Examples of the long chain fatty acid are fatty acids composed of single fatty acids such as caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, stearic acid, isostearic acid, nonadecanoic acid, arachic acid, behenic acid, lignoceric acid, oleic acid, sorbic acid, linolic acid, linolenic acid, and arachidonic acid. Fatty acids composed of these single fatty acids such as coconut oil fatty acid and palm kernel oil fatty acid can also be used.
A representative process for preparing Compound (I) via an acid halide is described below.
A long chain fatty acid is dispersed in a solvent such as methylene chloride, chloroform, carbon tetrachloride, benzene, toluene, xylene or n-hexane, and 1 to 5 equivalents of a halogenating agent is added thereto based on the long chain fatty acid to obtain a long chain fatty acid halide as a reaction product. Then, an amino acid is dissolved or dispersed in a solvent, and the above-mentioned long chain fatty acid halide is added thereto in an amount of 0.3 to 1.0 equivalent based on the amino acid, while maintaining the reaction solution at a temperature of 5 to 70xc2x0 C. and thus acylation is carried out to obtain Compound (I).
Examples of the solvent used for acylation are water, methanol, ethanol, isopropanol, isobutanol, acetone, toluene, tetrahydrofuran, ethyl acetate, N,N-dimethylformamide and dimethylsulfoxide, which may be used singly or in combination. In the step where an amino acid is dissolved or dispersed in a solvent, an alkaline substance such as sodium hydroxide or potassium hydroxide in an amount of 0.8 to 2.0 equivalents based on the amino acid may also be dissolved or dispersed in the solvent as may be appropriate.
In the case where a salt of Compound (I) is desired and it is produced in the form of the desired salt, it can be subjected to purification as such. In the case where Compound (I) is produced in the free state and its salt is desired, Compound (I) is dissolved or suspended in a suitable solvent, followed by addition of a base to form a salt.
Compound (I) is usually employed in the cleansing composition of the present invention in an amount of 1 to 90 wt %, preferably 3 to 80 wt %.
The cleansing compositions of the present invention may be formulated to contain adjuvants such as pigments, fragrances, solubilizing agents and builders, and also surfactants such as anionic surfactants, cationic surfactants, amphoteric surfactants and nonionic surfactants to adjust foaming and detergency.
Examples of the surfactants are fatty acid soap, higher alcohol ester sulfate, polyoxyethylene higher alcohol ester sulfate, higher alcohol ester phosphate, polyoxyethylene higher fatty acid ester phosphate, salt of sulfonated higher fatty acid, salt of sulfonated higher fatty acid ester, higher fatty acid ester isethionate, salt of xcex1-sulfo higher fatty acid ester, higher alkyldimethyl benzyl ammonium salt, higher alkylamine, higher alkyltrimethyl ammonium salt, higher fatty acid diethanolamide and its ethylene oxide or propylene oxide addition product, higher fatty acid monoethanolamide and its ethylene oxide or propylene oxide addition product, polyoxyethylene higher fatty acid monoethanol amide ester phosphate, salt of N-long chain acylamino acid such as salt of N-long chain acyl acidic amino acid, N-long chain acyl sarcosinate and salt of N-long chain acyl-xcex2-alanine, higher alkylamino propinonate such as laurylamino propionate, higher alkylimino diacetate such as laurylimino diacetate, and amine or amide compounds such as higher alkyldimethyl betaine, higher alkyl dihydroxyethyl betaine, N-alkanoyl-Nxe2x80x2-(2-hydroxyethyl)-Nxe2x80x2-carboxymethylethylenediamine, and N-alkanoyl-N-(2-hydroxyethyl)-Nxe2x80x2,Nxe2x80x2-biscarboxymethylethylenediamine.
The cleansing compositions of the present invention are useful as shampoo, facial washing compositions, bath soap, kitchen detergents, etc.